The present invention relates to carbon materials useful as structural materials used under severe conditions in terms of heat resistance, corrosion resistance and sliding characteristics, and as electrode materials in respect to conductivity and intercalation characteristics.
As methods for producing carbon materials which are having an important place in industrial materials, methods of carbonizing various kinds of organic materials at high temperatures have recently been proposed.
For example, carbon materials of good quality are obtained by carbonizing polymer materials. However, glassy carbon is so hard that it is very difficult to process carbonized products simple in shape into parts complicated in shape (Japanese Unexamined Patent Publication Nos. 61-275114 and 61-275115).
Further, production of carbon/carbon composite materials requires a multistage process comprising impregnating fibers with matrix resins such as phenol resins, carbonizing the resulting impregnated fibers, then impregnating the fibers with the matrix resins in an amount corresponding to a loss due to the carbonizing, and further carbonizing the impregnated fibers. Accordingly, the carbon/carbon composite materials are not used for general applications.
Then, if it becomes possible to form preforms having desired configurations from thermoplastic polymers excellent in formability and carbonize them, the applicability of carbon materials can conceivably be largely widened in terms of processability and production cost. From such a viewpoint, three-dimensional mesh type molecular composite materials are by far the best in stability in heating, compared with other materials, and expected to be useful for the above-mentioned purpose.
Further, rigid polymers are known to be easily graphitizable materials, and it is conceivable that new kinds of carbon/carbon nanocomposites can be formed by one-step carbonization as long as the fibril structure is maintained. Thus, development to unique functional carbon materials whose fine structure and characteristics can be designed by the amount of the rigid polymers added is expected.
An object of the present invention is to provide a carbon material which is an isotropic bulk material and excellent in physical characteristics, particularly in conductivity, by carbonizing a three-dimensional mesh type molecular composite material in which a rigid aromatic polymer or a reinforcing polymer is dispersed in a matrix polymer finely, homogeneously and sufficiently.
According to the present invention, there is provided a carbon material produced by mixing a matrix polymer with an aromatic heterocyclic copolymer precursor in which at least one functional group forming a heterocycle is substituted by another functional group, in an organic solvent to form a mixed solution, removing the solvent therefrom to form a coagulum, thereby preparing a three-dimensional mesh type molecular composite material, and then carbonizing the resulting composite material.
In the present invention, the carbon material is preferably an isotropic bulk material.
In this case, the matrix polymer is preferably a polyamide, and further, the aromatic heterocyclic copolymer is preferably at least one copolymer selected from the group consisting of polybenzothiazole copolymers and polybenzoxazole copolymers.